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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e40e975930e9c9629a17bfd6f5235346a8d87da705e7fc2c2cfc2dcae8c29532' 
  AND token = 'SlV4X/amloVkDatRitZS8Lr4aYcWp6HhUbqfGcjXUAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}