SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd924607f0c76171d0906495ffea1932b7bcb251249ea657395bf54a420e60a89' 
  AND token = '0zy0+QPhM795hjnbMwjWOn8YEuzJcdLk8gBGfDFmVPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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