SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83be2e408e967ef961c708e54ddf425d3dd4d09b6c9c9a2db0615f92da207f7b' 
  AND token = 'T7mk8GdfaZEgKZg34M1Owzckjm13MqPMsprW6P2bByY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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