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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '513296438d5d6f1509adf0bcb83e1c7e0cb85155f3f94e03d7c7ce3919c55726' 
  AND token = 'nkJZhgFkn5cNchJbj2SsZ5QNtTlSYqZmVEqXIiQeBVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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