SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ca856d518f20954458dd372649a7d43f71648bc871c017b901be2a4d5ed4255' 
  AND token = 'LqhaSH0FvKRaTP3qjBbn9Otscj/qrvFH4pOeFwjAsmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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