SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a4a684050cfa8a171006e634c80501afbb5fe7b7ed90f9ef916bc1794d1401c' 
  AND token = 'KVUkVY7YP/DoQT8JSTGnF6dvw2/aljQVpSJNdwEthLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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