SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5387f84e822d37b7f44622c895a657699909d8fe29d457b5fd87509c6fd4bfb' 
  AND token = 'bmKqEzDbUOlMtBfhWHnBzmZnyRAxtwCRru6bxi/eMXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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