SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ff3607ff4b8cda379007770b03a280eb18409677afcce62b977f76eca5b75ed' 
  AND token = 'frcnEE+QuF12i+gIquxw6dqSmZBUBuAs6b3ZAt/Wp9I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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