SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9d7187f781bf5d257bb0be8f67942762a64810d24a75439c9f8dbfd92f17cce' 
  AND token = 'S68bSIGt+LyQsK6YOmptSH3EeJ4GSjRvmYcv1MN22pA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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