SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '372d69c41f8de45de94646e6198311adb0b672c93704c3857caeecf6756df71b' 
  AND token = 'ISYiRyBXGYj7oLwtt7+KuuLB80g2JcsQSNMoUemBYqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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