SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6211e4680e6ac84fad71f449913467cc4b4bef8ca44546be59c3631355103ec' 
  AND token = 'JjSjC7dfFVIcr3mR4WsdN1/dtNtbakqJsYctUy892eA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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