SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03ef6857cd05f5437e52f1697fa3646dd7af7f85df09dfe52e6afacbadef54ab' 
  AND token = 'CUO8WNJRcGTZUCRlASetArNSDpT3+NwP/bv4VuvQ0YI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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