SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66a3431ddfbc28c2a93371fbc8fbf9f24080e651d793b25365e5d639a877b8f2' 
  AND token = 'OxSD4RmIh0e0VflHoTkTiMBrAAhsIXjxVlEwX9JoVKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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