SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab50e81e89852ac237b1c605a87a9456833130cd82c5f78166e7605d1346bc68' 
  AND token = 'ghX20rF/V3T7FxQiHlwIhjBbwFZpr8gNPQgXO/f/Icg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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