SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '494571df9c2b5fc62bfa425ca7a93ac3286642be2fc97bbe31170898ebe605bc' 
  AND token = 'bjSRhBfp+QICvMHx53LG2PpQW87Rv3/agMVgmKtg6lg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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