SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ebd2ba95aada54e4879481e92ff3d021eda95a874e663d57333874f1a54d311' 
  AND token = 'UvEMM0HV40tqFuf3gFakPrrHJ99G6mVNNvYkClI+2Xk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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