SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99a914125c960da5f9ffd848d371413758ae91aacf67ccf5238b8ff2f7920f86' 
  AND token = 'WiU2fglGaVxbScbBy4rfxTlJKVsVrlqwyRuOfMIAYMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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