SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e912afef3988b98a7562f16ea8bc12b605bddcbd34e46757daf04441048e009' 
  AND token = 'EfGFxTTOXf8hlQ1uAQnjQBYIkuzXCu2Nwaqtc8fh+qI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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