SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fecd8015e33356664e14554b68add76a0f64906afaa590e784013356382e046f' 
  AND token = 'GJCeCLViU5SjntkDllcW6doWntiNumR+kYYbDdLzka8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}