SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75090eda40f3eb376b8e0d5f370e3bf798652636f8a4db3c73584d7ccbba3699' 
  AND token = 'hLBQS1JfoS+xOq4ksWAYUkR8iVkwjsHJgKwkwFah5Dk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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