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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35993e6a37744851fabc0f14412c7ce4de4e3666dd252711e31508e1a8af4f2c' 
  AND token = 'DQ2QYdoMQlAclsDDQUmBbe7IPe5SMYY73ZYg/Dkduh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}