SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ed756135d0ba37ee04c0f606259da98167866c5e51b153eafb8a8b545f00079' 
  AND token = 'OtWIdTxu5ZQY875jJBmE/2G+7VX8WsiPrO36XHySGUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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