SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f2406e04adb1db06b12bf8fdc1d5986b24d448a1eb5d875a5e8b37991ea90cc' 
  AND token = 'uHMuW5vJHdiSl8IuVjJR4mLZFIdYBMWaOXiHKHdFHJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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