SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27a15787047f3db069f67c7b59583e2e38c2491aa3ad35b645ee37b3693ddc5f' 
  AND token = 'xYQyGahC0DsLaVnZyZqVFVWRrqjw+sCxBvmxoO1nmRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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