SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9519f0a444ab42b25583c54cdeec1fb557b066cc2e7962719787a0e9a305f90' 
  AND token = 'UBSQ0EYd0mdvrqmkOQlZah3NyAzEoIWRWtGbvUojIcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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