SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4d91b02dc31ff7597646f50f457d4070ae66293e3d6aec6dcb5ff9b9dcae000' 
  AND token = 'Swx/qnsvBBDexlDdgMh0ZXiaHEqv2Xd5nFAuzKXhK78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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