SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9297a5ca9d0cf6877623ac4f45a3257eb808d8dc78c19697db5dda7a5de75f93' 
  AND token = 'znkWDquCr+LS6jQ/RyxkQ/+IUbL82n9fVLPO59ES2qk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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