SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3943c3f1afdf680fc7f5bcf7203038d85fc9f2ebb22e162afa639653659a3dd6' 
  AND token = 'vZEGIkq7e3WuLLzDLhuIgLXCmx+6VLOMIAPs7WBqOQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

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