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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b12b30c129a6162df741413a0e75d16ce678e1b4b7e170446ae09f1fa41576f6' 
  AND token = 'nUbysbs2/cVb0L3XV5sM8mJCNqqANQYZtVHGJL/MlUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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