SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b157033fdcc71cae44065d18ac097f847547e8622114d2232776c515218720aa' 
  AND token = 'IJJT5sReDbSReO5/nZMEx/NFol6YmteSrNkc052Wipc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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