SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4d5b13b5cae6b5c2621969d8782f4da5ca7aa61825e56fcda011cf5290d5cfe' 
  AND token = 'yLLkmEKSeqZZsMhnYWhk4sI1bYAGYAyqMMCTi4SyC6k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00064

JSON explain

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