SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd347a37fa36bc7c741a1f89a51ef4788e43b1d0d599c4b6f339d85fbb36b42f8' 
  AND token = 'y5hgLwGul7eArqGu4TQCBjyA8pGkJ3Ja+LmPNNTJhRw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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