SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e5e21b9f96760005412c847aa39acb175e3fa5fb2f861e82a5b85a392aaaffa' 
  AND token = 'LGcKkDbY3Ml6NHFlwakchf9nDxMLn1I+Nw+rZJlbrzs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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