SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c407983eaa50934a868449759533480b10411b1cbf6d496229f2cc7357947264' 
  AND token = 'jmVd/XnjQ0ENe/3vaLW4VZXVlCaxBbQwNFqRqBFDe2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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