SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d31a340b4342d4895ca640240ddf4d893bcd2dd165737edb36441037c672bd0' 
  AND token = 'c7h+hz1gbfWQnPYqZoeRYz3nX3kVkG8WX7o1DmTSATc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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