SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f0c687fa56fcc52a0aadc2759bf267cc7e24d82097db9a1e8b8a71201880d4a' 
  AND token = 'fooHJvQNbIr1zMctRqdh271HVax+ytZedPLbIkIMq0k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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