SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75cbcbd3d2b9b292d4b75d1694428c955dfd229e4e175f32fb93900fe6648e6d' 
  AND token = 'SjOQXYZhWk5viSGbJ4AhCDYW9n92UFlyaZg8GGVEdf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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