SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '48e20a73a9f277253f3df7d887aef45496a0baa01f7436e38dbdbe0a54f3752d' 
  AND token = '6PKJEOH4SZLv0GrMkJ9f9DZ8j1eHjw/jG03v/xg+BaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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