SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b70c741e209a00b4141c078b49542ced45959258179d91e5b8cfc360d075ad9e' 
  AND token = '/M5vG3XX/5qEZa66Ix2+Josgh5PznzBNAjfFlX4jmGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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