SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c951252ed1ba17b5ee2e5a8f861be99b4b28ce7fc1ed043d1ba82ae70705fedf' 
  AND token = 'E+MR0ourN/zIX8tml7NaXQ8bbn2P0qUPmJCdhSlQII8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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