SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50a38ab6825ae28e2fd178d668c388a0c6714b2c672bda92000c391ceeab07a4' 
  AND token = 'bChDDXvkP4xsgYMsoB4t9zuMucdb5onhqNCe9XPS5Qs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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