SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e977988d4b4c9c30909dcc4054d72bd8b5c54ea67785cf464aa916091eee60fa' 
  AND token = 'MUSvtatZS6VW3k34Ht3w0ye699frsWZdUGx1FYot72g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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