SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e6eb06752fede253670438ba52493a1794e484c4dd73f6d5df9bdbfa6d40df9' 
  AND token = 'fN6NSPAFb7C+ZRMZTfpOXg4ro9VszWD+whUYxTq4Jks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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