SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66ae16365c73f8ded10ea3bbf5dc4aeb111ad92c350b2b15d76828fd96231226' 
  AND token = '71oFwGICN7aFOlicKGpI/QD/h1bHZ+utEiAauVJjCf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}