SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8308a080d85df07584bc941344a59541dc656a815f22b67587d09bd3760fafa' 
  AND token = 'xBbNSwGQmcDpfum9oLYhZezJHeSjdiKlif6Qyd8Cwbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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