SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ac2f85ca38b7af9929359e598a794f2f86a90b1ac150220efa40b9aa4264f91' 
  AND token = 'xE+IFPo3fATmZEPZOb+ELE7spWb1lAFmbsuhsjkndVY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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