SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd34609d8411cf4b5fb47bcb52d9285cb4e9e205c378647056a984b971163f303' 
  AND token = 'hvYqE/Z45vAGgEsSYaertZltY21Xa4QiJUvgAqvSXeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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