SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cad03a00bd68f16e3d2df142f1c7722d496b21a5891b6702b1b4169d2133d088' 
  AND token = 'Q8Pcz5cVvJKVPE1hIV96IhWgJwcKxok5AZKY303EBFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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