SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a91dc8b188ad4ca1541c94833aacf50e720c303cb9c1ff843c50d01d062a586f' 
  AND token = '2XOImcgcs0+5n1b2WyWrEW0ecnAHpv/q8I1HulSfT14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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