SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c27887a2688e5443b9531ab1d4b2919fddb7b1d6cdd52c7a675c6d4b48ea25fe' 
  AND token = 'UgyBOImONJPlFXWV1Rw8MLliJPr6qPF5/yd3HV2v3nQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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