SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a0edfb30292d737c06f5212616abd140b2e0ed71d63c8a85681094f816b8e7a' 
  AND token = 'HvMaL8jLfUfUWjq5EHiv5cN1WsaZ6mP8AUJt2GDudjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}