SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46834a03af01a34d55b724e6d8462a841c547c256596ab3eb88e5d2dcadc1858' 
  AND token = 'Kn2/3bOwJB3S9TVXWAGCxjJQJb4Q/EAw+uh8/ibJhOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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