SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5255e15f70738b06f213018832796f0be3a92b4f320eeb7a6845578e64d532d' 
  AND token = 'tZFxTbOV3m6f4esVBfXLp7I0IxF806Nlyfs88jor93w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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