SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '95715731ae052ad8243e8b0938daa1f443e08dd6a746f981d8d2e5cda5c5e367' 
  AND token = '5GMqfgtCDZDSv2lvQFWDMrISPhzAsBi/hlJBS7R7oMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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