SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20d1d909f12a090b8750166488c98eae331e40dfa49dfddc54aa3f8a44ad7e65' 
  AND token = 'j6cBi0rV73ZeIZnqDrq+PW8ajD4I4Cj4rHiaOi98PdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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