SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42b9ab87b8543fb5ab4965d0c63b6b375cee801fd5826ffa7869f236be5328d1' 
  AND token = 'VQq9g/YYX5ky+WkW9dlGK5mIX9bR/hggH0heA8Up1I8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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