SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8bb4fd04c8646db806e581d0a57e93dfd7cc52930364fd1006f32a10862852d' 
  AND token = 'Ivv9xFGDyanZIjP8nYN+GQgWIV/AsV0sKAPlgB7dL0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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