SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f77917ea159f19a1c7737847fad40f57a051fe4ae840d6d05808d2dfeead28f' 
  AND token = '6rmET01+aCVhmC6cSmxfofZM36yiQQeBRsjqSaHJ8WY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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