SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f50e2511a3f004f3b3ef9c60d64df378095c25d9915b36f21de21e78dfe0ad4' 
  AND token = 'gmDL4SZ8Yf2nQQc8NyMKgzhOtF/VvHpFuljRAiOybaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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