SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd75b52ccb55ac16ec125be37a8fb1b01b66fe8e65eb459284f75220b03053ce5' 
  AND token = 'VWKut2uxX2ot/kzPm5JYlgryxhz2UeDk+N27SIyQgEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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