SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c0254d81dfb82cd0af8d4b322f3a9d2caea99c69bd8e43f1ecf74639b387417' 
  AND token = 'kuYSVarlRM7MEmysNWDJ1ex3yfLIfESFL6BDlifuVdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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