SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc21b27c12ad616d0fd2d35f5f311f8295d30e10b961b943c574810fadfc2d05' 
  AND token = '2BJQXirPbazKckKyAFdEv3M+ZoSEvZoPfxpzGeCAgD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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