SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c5eddfc6c5def5be29c4a052397e8b21d6813d204b74bd6000f127d9d8e44b91' 
  AND token = '7+oZ5qxg4+zUo1JV82TGBak+ymf+CM31/LKdMwK+aUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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