SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3770b010b585e9bd66d76a29e52762339c639e03ab4a13faecdf0876b994657' 
  AND token = 'zxpVynI+yAMRgZTmDu1qO1DXUb6id1+wTqEFcaYaKok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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