SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b275686e1ea49188fdb4f1648fdbda2f5e2b42277e5eac684c6197ba423bcf03' 
  AND token = '3I1CvhZo/cseuvQkDuH7QOgRFZVCzboJxmPupBZuZGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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