SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b47de93407a0aee26e5e2bc4070e75ee04a035b8e484177161298fddf509cda' 
  AND token = 'racoljfl2UYGxV+d6CrPKJ1014bbl7C4iVu80/eJmxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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