SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03bd59b00289ab76e4789d553fea611f6daaf3aa8369a286627b685d774a9b41' 
  AND token = 'MhgkVxP3nbcV7Vmd2WsRoX8s5atcM5rWgANCbExAThE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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