SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cf63d118248955b7e5bd6ac55a7f7ba86dacbc68cc443b4a257b3c69af8e4c6' 
  AND token = 'hhIU8TiXnJN8iNbuRQLEjdxBgNxL0C0g/xs7LAIkV4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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