SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f15c1ae180bd40edf534734d4f3ffbe35d0a7e02307bf218dcadfbd9e8e2675e' 
  AND token = 'Q+XDYhiIzknCPcxidSkDaT+XDGs5RVaaRMa/pqSPLxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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