SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a4db9bb81d85e0a4058a1910e99e9afe63a222f22bf3d16ea95115657446bcc' 
  AND token = 'eQbZaEagUkKRj+8VlLgoGlhCNH+JxE7qxgBrU+qAVXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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