SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36f98a68165ec9571868e96d6f9e33f5d09287c0716fc363f7dabea3a8b0b85d' 
  AND token = 'CmcFvh2gYNxQc5Dp/ljFUSywyVYMzsSecfv0AJAgqdg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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