SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16db9daf00d7b74109c68bbdbf099c6edced7e60057603323e92820602a4fb0c' 
  AND token = 'MEm10NIdYfJzjhV95OKhHKTXLOHSR6lYPdJmuq02Xps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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