SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '300c34dfe30dc790284cd4d62384132cada6255fd95dca379cf3ff6909ce490b' 
  AND token = '2nW/iEZTQXdOWw+VlWYYeYpfgwgC2zts/gAcFg2y0dk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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