SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b39d1dfb8d9f557cd5d32a60cc9fe17a9739083a584f1638ea4ad0e4993265f' 
  AND token = 'jgZsSR+mybLrjLb58CFGeCY0n9+lNkkiHvlvmnyhGXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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