SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3364a57ce7c9328c19de684f823978528e3fec96e9f5bb40cb0260c545fbf546' 
  AND token = 'bzx6bNi5pmFRaGJ+NUovIQpv83n3pBJ/Z1ABQH4uKFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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