SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc83633ec1594ec167b4d83cea1721995825120f65967bbe0ba36b362ced32e9' 
  AND token = '2hUvpCOHXp/8wNxir02ReC8BOWGKg+co1Lb7jp/5Jmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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