SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '084b998bfeda026ee4917e9a4ab5c00614547022ca60cee6a1fd5ec67c335403' 
  AND token = 'H3eTvrHVibN7Oms4/TMoXVdEGT6a1zDF8Y22iivEgas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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