SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '425b1ee883c9eeade6520b29bfec79c269da3fccf52e1ebc7599090eca7503f7' 
  AND token = 'FTUk/qPaaKv5cEx+uU1zE9QamVydjreizE/6iKL0+Yk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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