SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b9ffca32815554c2f2a1738ba04f703fe081c742c5a124d438de746b80c0ba3' 
  AND token = 'WxAPjELZJR8nSpINL3HfEO8ge1AfRELaP0iQ8kXpgpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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