SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa2784293e37316ae08fe800a688d7c49b515404f5f82ef41f4191f068ebef79' 
  AND token = 'l76j08ZlOpF6Vu0SofOcSA64i87tTRFMCx1Y0CsEAjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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