SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad5d1e554f9d32e28abbe3e31ab975c9e757d22ebdbe9f07b988f189392e6640' 
  AND token = 'VMLRs7NvbnWg8jGRaoOVzBslqFLh3d8dqkPJoZIGkrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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