SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb10455a846889016deae3c3c652b3fc29737c449ad050cff99f3fb848186247' 
  AND token = 'OEIjgpgTCEHZ2na3rZWv+NQ9K+5R8YVbSockWFzWpUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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