SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44f23fbce1c06dafa5502723feb2b7a531515cb80b0788a6827f35dc5af1527c' 
  AND token = 'pSSFD1YW37inRAifgzy36s4AQlB4iBHtBtL8woG8HDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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