SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6ca2025ba68b4745f2f2748ba739e9e76dbbfe679a1151a6e87f88232596830' 
  AND token = 'fXVKEE96GwrlQ9A1OVGvv7Sq1Ya3Nfgp45Qgg2yhXcc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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