SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f708a2f1899f2fcc0fb64b0a072d65cda491effce502503436d2434698769304' 
  AND token = 'HelUNDqoVPKoRzDQt6canlUIsquoCw7Y1mFeckzpAF8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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