SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2017d188a3bc32b869b542264e722ffee0f8d581fad9a2a655bce8b84fac858' 
  AND token = 'JXjmpffvH65Bh71RUfz0dFFvbfFtkUZmJTmDz18zTtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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