SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f6abaff5e25a8a89f29a0374be4d857147b8f8c9fa84f8e6033d3ba33a163fc' 
  AND token = 'HLMf4TKbMv+BzPxJ7sE1ytyMjMTVaJWzXmYzJOxF08Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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