SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '046a8a3017dda291e497e08c0a149999bf7a0be342d455277d73af708449e9eb' 
  AND token = 'cpPE7cP26BXDkO0VKwpSVOlhMLhY+pMexezCk0JHh1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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