SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78c689b5aa61850b30f27fe18522f27c1fd9ffff6e414487f17e1669e18b548b' 
  AND token = 'HwKqcAOHl3NOYdoelwXTJiU4uRry/sVKZnRhLJ5KM00=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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